The isoelectric point is one of the qualities commonly used in the scientific community to characterize analytes. Many biomolecules (e.g., amino-acids, proteins, and peptides) have an isoelectric point. The isoelectric point (pI) of a molecule in a liquid is the pH value at which the molecule has a zero net charge. As the pH of a buffer in which the molecule resides approaches the molecule's pI, the net charge of the molecule approaches zero, which results in a diminishing electrophoretic mobility. Devices and methods for determining the isoelectric point of biomolecules and other analytes would therefore have significant commercial value, for example, in drug discovery and other pharmaceutical research, pharmaceutical and other chemical testing and production processes, and the like.
A need exists for new methods and devices for determining the isoelectric point of a charged analyte. A further need exists for simpler electrophoretic methods and devices that can effectively separate a mixture of charged analytes, e.g., a mixture of biomolecules, into its component analytes and to determine the isoelectric point of all or some of the component analytes. It is an object of the present invention to fulfill one or more of these needs and in certain preferred embodiments to provide further related advantages. From the following disclosure and the detailed description of certain preferred embodiments, additional objects of the invention and objects of certain preferred embodiments of the invention will be apparent to those skilled in the art, i.e., to those having skill and experience in this area of technology.